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want to insert a new range into the middle of the vector, then delete ranges one at a time next to the inserted one as they are merged. Instead, if the inserted interval overlaps, just start merging. The only time we insert into the middle of the vector is when we don't overlap at all. Also delete blocks of live ranges if we overlap with many of them. This patch speeds up joining by .7 seconds on a large testcase, but more importantly gets all of the range adding code into addRangeFrom. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15141 91177308-0d34-0410-b5e6-96231b3b80d8
194 lines
6.1 KiB
C++
194 lines
6.1 KiB
C++
//===-- LiveInterval.cpp - Live Interval Representation -------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the LiveRange and LiveInterval classes. Given some
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// numbering of each the machine instructions an interval [i, j) is said to be a
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// live interval for register v if there is no instruction with number j' > j
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// such that v is live at j' abd there is no instruction with number i' < i such
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// that v is live at i'. In this implementation intervals can have holes,
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// i.e. an interval might look like [1,20), [50,65), [1000,1001). Each
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// individual range is represented as an instance of LiveRange, and the whole
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// interval is represented as an instance of LiveInterval.
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//
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//===----------------------------------------------------------------------===//
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#include "LiveInterval.h"
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#include "Support/STLExtras.h"
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#include <ostream>
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using namespace llvm;
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// An example for liveAt():
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//
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// this = [1,4), liveAt(0) will return false. The instruction defining this
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// spans slots [0,3]. The interval belongs to an spilled definition of the
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// variable it represents. This is because slot 1 is used (def slot) and spans
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// up to slot 3 (store slot).
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//
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bool LiveInterval::liveAt(unsigned I) const {
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Ranges::const_iterator r = std::upper_bound(ranges.begin(), ranges.end(), I);
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if (r == ranges.begin())
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return false;
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--r;
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return r->contains(I);
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}
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// An example for overlaps():
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//
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// 0: A = ...
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// 4: B = ...
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// 8: C = A + B ;; last use of A
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//
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// The live intervals should look like:
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//
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// A = [3, 11)
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// B = [7, x)
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// C = [11, y)
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//
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// A->overlaps(C) should return false since we want to be able to join
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// A and C.
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bool LiveInterval::overlaps(const LiveInterval& other) const {
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Ranges::const_iterator i = ranges.begin();
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Ranges::const_iterator ie = ranges.end();
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Ranges::const_iterator j = other.ranges.begin();
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Ranges::const_iterator je = other.ranges.end();
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if (i->start < j->start) {
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i = std::upper_bound(i, ie, j->start);
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if (i != ranges.begin()) --i;
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} else if (j->start < i->start) {
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j = std::upper_bound(j, je, i->start);
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if (j != other.ranges.begin()) --j;
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} else {
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return true;
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}
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while (i != ie && j != je) {
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if (i->start == j->start)
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return true;
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if (i->start > j->start) {
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swap(i, j);
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swap(ie, je);
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}
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assert(i->start < j->start);
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if (i->end > j->start)
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return true;
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++i;
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}
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return false;
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}
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/// extendIntervalEndTo - This method is used when we want to extend the range
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/// specified by I to end at the specified endpoint. To do this, we should
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/// merge and eliminate all ranges that this will overlap with. The iterator is
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/// not invalidated.
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void LiveInterval::extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd) {
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assert(I != ranges.end() && "Not a valid interval!");
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// Search for the first interval that we can't merge with.
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Ranges::iterator MergeTo = next(I);
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for (; MergeTo != ranges.end() && NewEnd >= MergeTo->end; ++MergeTo)
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/*empty*/;
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// If NewEnd was in the middle of an interval, make sure to get its endpoint.
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I->end = std::max(NewEnd, prior(MergeTo)->end);
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// Erase any dead ranges
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ranges.erase(next(I), MergeTo);
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}
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/// extendIntervalStartTo - This method is used when we want to extend the range
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/// specified by I to start at the specified endpoint. To do this, we should
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/// merge and eliminate all ranges that this will overlap with.
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LiveInterval::Ranges::iterator
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LiveInterval::extendIntervalStartTo(Ranges::iterator I, unsigned NewStart) {
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assert(I != ranges.end() && "Not a valid interval!");
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// Search for the first interval that we can't merge with.
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Ranges::iterator MergeTo = I;
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do {
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if (MergeTo == ranges.begin()) {
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I->start = NewStart;
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return I;
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}
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--MergeTo;
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} while (NewStart <= MergeTo->start);
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// If we start in the middle of another interval, just delete a range and
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// extend that interval.
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if (MergeTo->end >= NewStart) {
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MergeTo->end = I->end;
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} else {
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// Otherwise, extend the interval right after.
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++MergeTo;
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MergeTo->start = NewStart;
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MergeTo->end = I->end;
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}
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ranges.erase(next(MergeTo), next(I));
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return MergeTo;
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}
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LiveInterval::Ranges::iterator
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LiveInterval::addRangeFrom(LiveRange LR, Ranges::iterator From) {
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unsigned Start = LR.start, End = LR.end;
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Ranges::iterator it = std::upper_bound(From, ranges.end(), Start);
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// If the inserted interval starts in the middle or right at the end of
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// another interval, just extend that interval to contain the range of LR.
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if (it != ranges.begin()) {
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Ranges::iterator B = prior(it);
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if (B->start <= Start && B->end >= Start) {
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extendIntervalEndTo(B, End);
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return B;
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}
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}
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// Otherwise, if this range ends in the middle of, or right next to, another
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// interval, merge it into that interval.
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if (it != ranges.end() && it->start <= End)
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return extendIntervalStartTo(it, Start);
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// Otherwise, this is just a new range that doesn't interact with anything.
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// Insert it.
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return ranges.insert(it, LR);
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}
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void LiveInterval::join(const LiveInterval& other) {
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isDefinedOnce &= other.isDefinedOnce;
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// Join the ranges of other into the ranges of this interval.
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Ranges::iterator cur = ranges.begin();
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for (Ranges::const_iterator i = other.ranges.begin(),
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e = other.ranges.end(); i != e; ++i)
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cur = addRangeFrom(*i, cur);
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weight += other.weight;
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}
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std::ostream& llvm::operator<<(std::ostream& os, const LiveRange &LR) {
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return os << "[" << LR.start << "," << LR.end << ")";
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}
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std::ostream& llvm::operator<<(std::ostream& os, const LiveInterval& li) {
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os << "%reg" << li.reg << ',' << li.weight;
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if (li.empty())
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return os << "EMPTY";
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os << " = ";
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for (LiveInterval::Ranges::const_iterator i = li.ranges.begin(),
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e = li.ranges.end(); i != e; ++i)
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os << *i;
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return os;
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}
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